Actuators

18 pages, 8535 KiB

Open AccessArticle

Rotary–Linear Type Piezoelectric Actuator Based on Double-Elliptical Stator

by Andrius Čeponis and Dalius Mažeika

Actuators 2024, 13(12), 478; https://doi.org/10.3390/act13120478 - 25 Nov 2024

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This paper introduces a novel piezoelectric actuator designed for precise linear and rotational movements of a cylindrical slider-rotor. The actuator’s design features two elliptical frames interconnected by two plates, with a cylindrical contact situated on the top of the upper plate to facilitate [...] Read more.

This paper introduces a novel piezoelectric actuator designed for precise linear and rotational movements of a cylindrical slider-rotor. The actuator’s design features two elliptical frames interconnected by two plates, with a cylindrical contact situated on the top of the upper plate to facilitate the motion or rotation of the slider. Two piezoelectric multilayer transducers are housed within each elliptical frame and are used to excite vibrations of the elliptical frames using two harmonic signals with a phase difference of π/2 and varying excitation schemes. This excitation pattern generates elliptical motion trajectories of the contact in two orthogonal planes, enabling both linear and rotational displacements of the slider-rotor. Numerical and experimental investigations were conducted to validate the performance and accuracy of the actuator. Additionally, harmonic response and transient analysis were performed to investigate elliptical motion trajectories of the contact in perpendicular planes under various excitation schemes and frequencies. The results confirm that the rotational and linear motions of the slider-rotor can be independently controlled. The actuator achieved a maximum rotational speed of 163.1 RPM and a maximum linear speed of 41.4 mm/s, with a corresponding peak output torque and force of 236.1 mN·mm and 368.1 mN, respectively. A resolution measurements showed that the actuator can achieve an angular resolution of 1.02 mrad and a linear resolution of 53.8 µm. Full article

(This article belongs to the Section Actuator Materials)

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15 pages, 8248 KiB

Open AccessArticle

A Lightweight, Simple-Structure, Low-Cost and Compliant Twisted String Actuator Featuring Continuously Variable Transmission

by Chanchan Xu, Tong Liu, Shuai Dong, Yucheng Wang and Xiaojie Wang

Actuators 2024, 13(12), 477; https://doi.org/10.3390/act13120477 - 25 Nov 2024

Viewed by 229

Abstract

Twisted string actuators, which are an emerging artificial muscle, efficiently convert rotary motor motion into linear load movement, with advantages like high transmission ratio, compliance, simple structure, and long-distance power transmission. However, the limited range of transmission ratio adjustment remains a challenge. Thus, [...] Read more.

Twisted string actuators, which are an emerging artificial muscle, efficiently convert rotary motor motion into linear load movement, with advantages like high transmission ratio, compliance, simple structure, and long-distance power transmission. However, the limited range of transmission ratio adjustment remains a challenge. Thus, this paper introduces a novel twisted string actuator design that automatically and continuously adjusts its transmission ratio in response to external loads. Utilizing lightweight hyperelastic slender rods, the twisted string actuator with continuously variable transmission achieves a simple, compact, and cost-effective design. By manipulating the distance between two twisted strings through rod deformation, the transmission ratio continuously adapts to varying load conditions. Mathematical models of the twisted string actuator with continuously variable transmission are derived and experimentally validated, demonstrating a 2.1-fold transmission ratio variation from 0.1 kg to 1.5 kg loads. Application in an anthropomorphic robot finger showcases a 6.2-fold transmission ratio change between unloaded and loaded states. Our twisted string actuator with continuously variable transmission offers unparalleled advantages in weight, cost, simplicity, compliance, and continuous transmission ratio adjustability, making it highly suitable for robotic systems. Full article

(This article belongs to the Special Issue Actuator Technologies and Control: Materials, Devices and Applications)

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22 pages, 8930 KiB

Open AccessArticle

Design, Control, and Testing of a Multifunctional Soft Robotic Gripper

by A. Correia, T. Charters, A. Leite, F. Campos, N. Monge, A. Rocha and M. J. G. C. Mendes

Actuators 2024, 13(12), 476; https://doi.org/10.3390/act13120476 - 25 Nov 2024

Viewed by 287

Abstract

This paper proposes a multifunctional soft robotic gripper for a Dobot robot to handle sensitive products. The gripper is based on pneumatic network (PneuNet) bending actuators. In this study, two different models of PneuNet actuators have been studied, designed, simulated, experimentally tested, and [...] Read more.

This paper proposes a multifunctional soft robotic gripper for a Dobot robot to handle sensitive products. The gripper is based on pneumatic network (PneuNet) bending actuators. In this study, two different models of PneuNet actuators have been studied, designed, simulated, experimentally tested, and validated using two different techniques (3D printing and molding) and three different materials: FilaFlex 60A (3D-printed), Elastosil M4601, and Dragonskin Fast 10 silicones (with molds). A new soft gripper design for the Dobot robot is presented, and a new design/production approach with molds is proposed to obtain the gripper’s PneuNet multifunctional actuators. It also describes a new control approach that is used to control the PneuNet actuators and gripper function, using compressed air generated by a small compressor/air pump, a pressure sensor, a mini valve, etc., and executing on a low-cost controller board—Arduino UNO. This paper presents the main simulation and experimental results of this research study. Full article

(This article belongs to the Special Issue Soft Actuators and Robotics—2nd Edition)

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19 pages, 1227 KiB

Open AccessArticle

Stability of Stochastic Coupled Networks with Time-Varying Coupling Under Intermittent Event-Triggered Control

by Yongbao Wu and Jiayi Bing

Actuators 2024, 13(12), 475; https://doi.org/10.3390/act13120475 - 24 Nov 2024

Viewed by 247

Abstract

This paper studies the exponential stability in the mean square of the stochastic complex networks with time-varying coupling under an intermittent dynamic event-triggered control. A dynamic term and an exponential function are introduced into the event-triggered mechanism to reduce the number of control [...] Read more.

This paper studies the exponential stability in the mean square of the stochastic complex networks with time-varying coupling under an intermittent dynamic event-triggered control. A dynamic term and an exponential function are introduced into the event-triggered mechanism to reduce the number of control updates. Simultaneously, the minimum inter-execution time for every sample path solution of the stochastic complex networks, independent mathematical expectation, is obtained. Unlike previous research, the event-triggered mechanism under the stochastic version is more reasonable due to the absence of mathematical expectations in the event-triggered function. Furthermore, using the average control rate for intermittent strategy and the Lyapunov method, sufficient conditions for exponential stability in the mean square under intermittent dynamic event-triggered control are derived. Finally, an example with numerical simulations is provided to validate the feasibility of the theoretical results. Full article

(This article belongs to the Special Issue Intelligent Sensing, Control and Actuation in Networked Systems)

19 pages, 2415 KiB

Open AccessArticle

Enhanced Operation Mode Design and Motion Control of a Dual-Redundancy Electro-Hydrostatic Actuator

by Huatao Jin, Shuanglu Li, Yaobao Yin, Rui Guo, Cheng Fang and Jiangkun Zou

Actuators 2024, 13(12), 474; https://doi.org/10.3390/act13120474 - 23 Nov 2024

Viewed by 164

Abstract

In dual-redundancy electro-hydrostatic actuators (EHAs), the dual pumps are mainly designed for safety, where the cylinder is controlled mainly by one pump while the other one is standby for redundancy. However, such a strategy is basically like a single-pump-controlled system, and the flow [...] Read more.

In dual-redundancy electro-hydrostatic actuators (EHAs), the dual pumps are mainly designed for safety, where the cylinder is controlled mainly by one pump while the other one is standby for redundancy. However, such a strategy is basically like a single-pump-controlled system, and the flow from the pump may be inaccurate when the cylinder moves slowly, which will affect the motion control performance. A new dual-redundancy EHA is designed, and a series of corresponding operation modes are developed, enabling differential operation of the dual pumps. With the proposed operation modes, the inevitable flow inaccuracy problem of the single pump can be addressed through the coordination control of the dual pumps. In order to achieve better motion tracking performance, a model-based backstepping controller is synthesized, where the nonlinearities and uncertainties of the EHA are handled by model compensation and robust feedback design. Comparative simulations with existing control methods for EHAs are conducted and better motion tracking precision is achieved, especially during low-speed motion. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems)

30 pages, 2820 KiB

Open AccessArticle

Dynamic Analysis and Equivalent Modeling for a Four-Axle Vehicle

by Dequan Zeng, Wei Luo, Yinquan Yu, Yiming Hu, Peizhi Zhang, Giuseppe Carbone, Dongfu Xie, Huafu Fang and Letian Gao

Actuators 2024, 13(12), 473; https://doi.org/10.3390/act13120473 - 23 Nov 2024

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Abstract

This paper focuses on a comprehensive study of a four-axle vehicle, including dynamics analysis, equivalent modeling methods, and their comparison. Firstly, a linear two-degree lateral dynamic model is established, which has four drive axles and two steer axles. Secondly, the mathematical transfer function [...] Read more.

This paper focuses on a comprehensive study of a four-axle vehicle, including dynamics analysis, equivalent modeling methods, and their comparison. Firstly, a linear two-degree lateral dynamic model is established, which has four drive axles and two steer axles. Secondly, the mathematical transfer function expressions for the yaw rate and the centroid sideslip angle were derived on the basis of the model. The steady-state parameters, such as yaw rate gain G_γss, centroid sideslip angle gain G_βss, stability factor K_n, equivalent axial distance l_n, and equivalent centroid sideslip angle coefficient K_n’ were obtained by using the transfer functions. Then, the steady-state and transient characteristics are roundly discussed, including steady-state parameters, system root trajectory, frequency domain, and time domain. Some recommendations for the four-axle vehicle’s parameter design are also given. Finally, for a more simple and efficient analysis of response characteristics of four-axle vehicles and even n (n > 4) axle vehicles, the equivalent model is developed for the four-axle vehicle, and comprehensive analyses are presented with four equalization methods, which are based on the inner heart of the approximation triangle, the outer heart of the approximation triangle, the center of gravity of the approximation triangle and the compensation point. Following a thorough analysis of the four, it is determined that the inner approximation triangle solution approach is most suited for four-axle vehicles. Full article

(This article belongs to the Special Issue Advances in Dynamics and Motion Control of Unmanned Aerial/Underwater/Ground Vehicles)

16 pages, 3422 KiB

Open AccessArticle

Development of Rehabilitation Glove: Soft Robot Approach

by Tomislav Bazina, Marko Kladarić, Ervin Kamenar and Goran Gregov

Actuators 2024, 13(12), 472; https://doi.org/10.3390/act13120472 - 22 Nov 2024

Viewed by 220

Abstract

This study describes the design, simulation, and development process of a rehabilitation glove driven by soft pneumatic actuators. A new, innovative finger soft actuator design has been developed through detailed kinematic and workspace analysis of anatomical fingers and their actuators. The actuator design [...] Read more.

This study describes the design, simulation, and development process of a rehabilitation glove driven by soft pneumatic actuators. A new, innovative finger soft actuator design has been developed through detailed kinematic and workspace analysis of anatomical fingers and their actuators. The actuator design combines cylindrical and ribbed geometries with a reinforcing element—a thicker, less extensible structure—resulting in an asymmetric cylindrical bellow actuator driven by positive pressure. The performance of the newly designed actuator for the rehabilitation glove was validated through numerical simulation in open-source software. The simulation results indicate actuators’ compatibility with human finger trajectories. Additionally, a rehabilitation glove was 3D-printed from soft materials, and the actuator’s flexibility and airtightness were analyzed across different wall thicknesses. The 0.8 mm wall thickness and thermoplastic polyurethane (TPU) material were chosen for the final design. Experiments confirmed a strong linear relationship between bending angle and pressure variations, as well as joint elongation and pressure changes. Next, pseudo-rigid kinematic models were developed for the index and little finger soft actuators, based solely on pressure and link lengths. The workspace of the soft actuator, derived through forward kinematics, was visually compared to that of the anatomical finger and experimentally recorded data. Finally, an ergonomic assessment of the complete rehabilitation glove in interaction with the human hand was conducted. Full article

(This article belongs to the Special Issue Modelling and Motion Control of Soft Robots)

15 pages, 36468 KiB

Open AccessArticle

Adaptive NN Force Loading Control of Electro-Hydraulic Load Simulator

by Zanwei Chen, Hao Yan, Peng Zhang, Jiefeng Shan and Jiafeng Li

Actuators 2024, 13(12), 471; https://doi.org/10.3390/act13120471 - 22 Nov 2024

Viewed by 195

Abstract

To address the issues of derivative explosion in traditional backstepping control and the strong nonlinearity of hydraulic systems, this paper develops an adaptive neural network control method tailored for electro-hydraulic load simulators. Neural networks are employed to handle external disturbances, modeling uncertainties, and [...] Read more.

To address the issues of derivative explosion in traditional backstepping control and the strong nonlinearity of hydraulic systems, this paper develops an adaptive neural network control method tailored for electro-hydraulic load simulators. Neural networks are employed to handle external disturbances, modeling uncertainties, and the derivatives of virtual control inputs. First, the precise state-space equations of the system are derived. Next, the approximation property of neural networks is used to design an adaptive backstepping controller, and the symmetric barrier Lyapunov function is used to prove the boundedness of the controller and control parameters. Finally, experiments are conducted to verify the effectiveness and reliability of the control algorithm. The results demonstrate that the proposed control algorithm exhibits excellent tracking performance and effectively reduces control errors. Full article

(This article belongs to the Section Control Systems)

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16 pages, 1955 KiB

Open AccessArticle

Adaptive Recognition and Control of Shield Tunneling Machine in Soil Layers Containing Plastic Drainage Boards

by Qiuping Wang, Wanli Li, Zhikuan Xu and Yougang Sun

Actuators 2024, 13(12), 470; https://doi.org/10.3390/act13120470 - 22 Nov 2024

Viewed by 215

Abstract

The underground plastic vertical drains (PVDs) are a significant problem for shield machines in tunneling construction. At present, the main method to deal with PVDs is to manually adjust the parameters of the shield machine. To ensure that a shield machine autonomously recognizes [...] Read more.

The underground plastic vertical drains (PVDs) are a significant problem for shield machines in tunneling construction. At present, the main method to deal with PVDs is to manually adjust the parameters of the shield machine. To ensure that a shield machine autonomously recognizes and adjusts the control in soil layers containing PVDs, this study constructs a shield machine advance and rotation state-space model utilizing Bayesian decision theory for the judgment of excavation conditions. A Bayesian model predictive control (Bayes-MPC) method for the shield machine is proposed, followed by a simulation analysis. Finally, a validation experiment is conducted based on a Singapore subway project. Compared with traditional methods, the method proposed in this paper has better performance in the simulation, and it also has demonstrated effectiveness and accuracy in experiments. The research outcomes can provide a reference for the adaptive assistance system of shield machines excavating underground obstacles. Full article

(This article belongs to the Section Actuators for Land Transport)

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14 pages, 2335 KiB

Open AccessArticle

Multi-Objective Parameter Optimization of Rotary Screen Coating Process for Structural Plates in Spacecraft

by Yanhui Guo, Yanpeng Chen, Peibo Li, Xinfu Chi and Yize Sun

Actuators 2024, 13(12), 469; https://doi.org/10.3390/act13120469 - 22 Nov 2024

Viewed by 233

Abstract

A multi-objective grasshopper optimization algorithm (MOGOA) with an adaptive curve c(t) and the enhanced Levy fight strategy (CLMOGOA) was proposed to optimize the process parameters of rotary screen coating, setting the thickness and uniformity of the adhesive layer on the structural plates in [...] Read more.

A multi-objective grasshopper optimization algorithm (MOGOA) with an adaptive curve c(t) and the enhanced Levy fight strategy (CLMOGOA) was proposed to optimize the process parameters of rotary screen coating, setting the thickness and uniformity of the adhesive layer on the structural plates in spacecraft as its optimization objectives. The adaptive curve strikes a balance between global exploration and local development and accelerates the convergence speed. The enhanced Levy strategy helps the algorithm to escape local optimizations, increases the population diversity, and possesses dual searching capabilities. After multiple runs, the average values of the CLMOGOA’s reverse generation distance were 0.0288, 0.0233, and 0.1810 on the test sets, which were less than those of the MOGOA. The best Pareto-optimal front obtained by the CLMOGOA had a higher accuracy and better coverage compared to that of the MOGOA. Thus, it is indicated that the CLMOGOA managed to outperform the MOGOA on the test functions. In order to solve the optimization problem, 108 sets of process experiments were designed, and then the experimental data were used to train a Back Propagation Neural Network (BPNN), a Least Squares Support Vector Machine (LSSVM), and Random Forest (RF) to obtain the best prediction model for the process parameters. Considering the thickness and uniformity of the adhesive layer as the objectives, the improved algorithm was used to optimize the prediction model to obtain the optimal process parameters. The actual coating effect showed that the optimization algorithm improved the efficiency and qualification rate of the product. Full article

(This article belongs to the Section Aircraft Actuators)

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15 pages, 7374 KiB

Open AccessArticle

Hysteresis Compensation and Butterworth Pattern-Based Positive Acceleration Velocity Position Feedback Damping Control of a Tip-Tilt-Piston Piezoelectric Stage

by Helei Zhu, Jinfu Sima, Peixing Li, Leijie Lai and Zhenfeng Zhou

Actuators 2024, 13(12), 468; https://doi.org/10.3390/act13120468 - 21 Nov 2024

Viewed by 303

Abstract

In order to solve the hysteresis nonlinearity and resonance problems of piezoelectric stages, this paper takes a three-degree-of-freedom tip-tilt-piston piezoelectric stage as the object, compensates for the hysteresis nonlinearity through inverse hysteresis model feedforward control, and then combines the composite control method of [...] Read more.

In order to solve the hysteresis nonlinearity and resonance problems of piezoelectric stages, this paper takes a three-degree-of-freedom tip-tilt-piston piezoelectric stage as the object, compensates for the hysteresis nonlinearity through inverse hysteresis model feedforward control, and then combines the composite control method of positive acceleration velocity position feedback damping control and high-gain integral feedback controller to suppress the resonance of the system and improve the tracking speed and positioning accuracy. Firstly, the three-degree-of-freedom motion of the end-pose is converted into the output of three sets of piezoelectric actuators and single-axis control is performed. Then, the rate-dependent Prandtl–Ishlinskii model is established and the parameters of the inverse model are identified. The accuracy and effectiveness of parameter identification are verified through open-loop and closed-loop compensation experiments. After that, for the third-order system, the parameters of positive acceleration velocity position feedback damping control and high-gain integral feedback controller are designed as a whole based on the pattern of the Butterworth filter. The effectiveness of the design method is proved by step signal and triangle wave signal trajectory tracking experiments, which suppresses the resonance of the system and improves the bandwidth of the system and the tracking speed of the stage. Full article

(This article belongs to the Section Control Systems)

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26 pages, 10651 KiB

Open AccessArticle

Research on Speed Control Strategies for Explosion-Proof Diesel Engine Monorail Cranes

by Hai Jiang, Dongjie Wang, Jiameng Cheng, Penghui Li, Xiaodong Ji, Yang Shen and Miao Wu

Actuators 2024, 13(12), 467; https://doi.org/10.3390/act13120467 - 21 Nov 2024

Viewed by 278

Abstract

This paper introduces a control method tailored for the speed regulation of monorail cranes in coal mines. Initially, an analysis of the structure and load conditions of the monorail crane drive components is conducted to calculate the traction force, clamping force, and target [...] Read more.

This paper introduces a control method tailored for the speed regulation of monorail cranes in coal mines. Initially, an analysis of the structure and load conditions of the monorail crane drive components is conducted to calculate the traction force, clamping force, and target travel speed across varying operational scenarios. Subsequently, the hydraulic system schematic of the monorail crane is analyzed to develop a mathematical model for speed control, enabling the assessment of system stability using transfer functions. A simulation model of the monorail crane speed control loop is then created in AMESim, where fuzzy adaptive PID controllers and MPC controllers are optimized in a collaborative simulation with Simulink. Experimental findings reveal that in a single acceleration condition, both controllers demonstrate superior dynamic response compared to a traditional PID controller, with the MPC controller exhibiting an overshoot of merely 8.9%. In speed variation conditions, the MPC controller achieved a settling time in the range of 0.26–0.3 s. Notably, the MPC controller displays a maximum overshoot of 11%, substantially enhancing the dynamic response performance of speed regulation in monorail cranes. Full article

(This article belongs to the Special Issue Intelligent and Precision Control for Mechatronic/Electro-Hydraulic Systems)

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18 pages, 15595 KiB

Open AccessArticle

Vehicle Attitude Control of Magnetorheological Semi-Active Suspension Based on Multi-Objective Intelligent Optimization Algorithm

by Kailiang Han, Yiming Hu, Dequan Zeng, Yinquan Yu, Lei Xiao, Jinwen Yang, Weidong Liu and Letian Gao

Actuators 2024, 13(12), 466; https://doi.org/10.3390/act13120466 - 21 Nov 2024

Viewed by 234

Abstract

A multi-objective intelligent optimization algorithm-based attitude control strategy for magnetorheological semi-active suspension is proposed to address the vehicle attitude imbalance generated during steering and braking. Firstly, the mechanical properties of the magnetorheological damper (MRD) are tested, and the parameters in the hyperbolic tangent [...] Read more.

A multi-objective intelligent optimization algorithm-based attitude control strategy for magnetorheological semi-active suspension is proposed to address the vehicle attitude imbalance generated during steering and braking. Firstly, the mechanical properties of the magnetorheological damper (MRD) are tested, and the parameters in the hyperbolic tangent model of the magnetorheological damper are identified through experiments. Secondly, a simulation model of the whole vehicle multi-degree-of-freedom vehicle dynamics including magnetorheological damper is established, and the whole-vehicle Linear Quadratic Regulator (LQR) controller is designed. Then, the optimization design model of the joint vehicle controller and vehicle dynamics is established to design the optimization fitness function oriented to the body attitude control performance, and the attitude optimal controller is calculated with the help of multi-objective intelligent optimization algorithm. Simulation results show that the proposed control method is able to improve the body roll angle, body pitch angle, and suspension dynamic deflection well on the basis of ensuring no deterioration in other performance indexes, ensuring good attitude control capability of the vehicle and verifying the feasibility of the control strategy. Full article

(This article belongs to the Special Issue Magnetorheological Actuators and Dampers)

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Actuators, Volume 13, Issue 12 (December 2024) – 13 articles

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